MAA, and methyl methacrylate (MMA) are widely used in industry, mainly as monomers to make polymers having a variety of uses, such as acrylate fibers (polyMAA), cement in total hip or knee replacements (MMA), various optical glasses and lenses (PMMA). MAA can be used as a co-monomer together with MMA or ethyl acrylate to produce polymers used in coatings and slow release applications. MMA can also be used as co-monomer to produce polymers such as methyl methacrylate-butadiene-styrene (MBS). Materials can be obtained by blending PMMA with other polymers such as polyvinylchloride (PVC).
MAA is currently produced from petrochemical resources. It would be desired to find a route by which it can be produced from bio-based, renewable, non-fossil resources.
A reference relating to such a route is WO 2009/135074A2, the disclosure of which is hereby incorporated by reference. Herein a process is described by which MAA can be produced by fermentation of a renewable sugar feedstock of non-natural micro-organisms.
Another reference relating to such a route is US 2010/0035314A1, the disclosure of which is hereby incorporated by reference. Herein a process is described by which MAA can be produced by catalytic dehydration of 2-hydroxy-2-methylcarboxylic acid obtained by fermentation, of a renewable sugar feedstock of non-natural micro-organisms.
Another reference relating to such a route is the work described by Pyo et al. (Green Chem. 2012, 14, 1942), the disclosure of which is hereby incorporated by reference. Herein a process is described by which MAA can be produced by a consecutive microbial conversion and catalytic dehydration of 2-methyl-1-3-propanediol, potentially obtained by fermentation of biobased glycerol.
Another reference relating to such a route is WO 2010/058119A1, the disclosure of which is hereby incorporated by reference. Herein a process is described by which MMA can be produced by reaction of methyl propionate and formaldehyde. Methyl propionate is produced by carbonylation of ethylene in the presence of methanol where at least one of the three reactants used are obtained from biomass: ethylene by dehydration of bio-ethanol and/or carbon monoxide and methanol obtained by biobased syngas. Formaldehyde can be produced from biobased syngas.
Another reference relating to such a route is WO 2012/154450A2, the disclosure of which is hereby incorporated by reference. Herein a process is described by which MMA can be produced by successive reactions (dehydration, formaldehyde aldol condensation, esterification) starting from biobased glycols such as ethylene glycol and propylene glycol.
Another reference relating to such a route is WO 2012/089813, the disclosure of which is hereby incorporated by reference. Herein a process is described by which MAA can be produced from the decarboxylation of itaconic acid or a source thereof in the presence of base catalysts. Although this process is interesting, the yield of MAA is far below a value that would render the process of commercial interest. Whilst the yield can be increased by raising the reaction temperature, this goes with a dramatic reduction of selectivity. Also, the high temperatures per se, and the high pressures applied, make the process less interesting, if not plainly prohibitive, for economic application.
It would be desired to provide a process that allows to produce MAA in a good yield, yet with a high selectivity. Also, it would be desired to provide a process that is economically more attractive by allowing lower energy input, e.g. by requiring a lower reaction temperature, and without applied pressure.
Further, the known process is applicable to itaconic acid, its isomers. The reference mentioned that the process is also applicable to a source of these acids. However, from the disclosure itself it is clear that the actual process far making MAA is not directly applied on precursors of itaconic acid, such as citric acid. Background art on making methacrylic acid from citric acid is Carlsson et al., Ind. Eng. Chem. Res. 1994, 33, 1989. Herein a low yield, 6%, of methacrylic acid is obtained, via a dehydration reaction and two decarboxylation reactions. It would be desired to provide a process that would be directly applicable to itaconic acid precursors, particularly to citric acid, and by which methacrylic acid can be produced in better yield.